The partial section of the trigeminal sensory root by the temporal approach, as perfected by Spiller and Frazier from the Hartley-Krause operation for the relief of trigeminal neuralgia, has been acclaimed the most perfect operation known to surgery. A certain degree of morbidity indicates that this perfection is only relative. In search of a better treatment for this disease, Dandy1 in 1925 began cutting the sensory root near the pons by the subcerebellar approach. While this operation has improved some morbidity rates, it has not eliminated them. Because the depth and location of the point of rhizotomy expose other nerve roots and important blood vessels to operative trauma, the majority of neurosurgeons have not discarded Frazier's operation in its favor.
One of the important by-products in the development of the suboccipital approach was the disclosure of a previously unrecognized frequency of gross etiologic lesions. In the first 200 cases